Plastic optical fibers and optical fiber cables

Abstract

PCT No. PCT/JP96/01270 Sec. 371 Date Nov. 14, 1997 Sec. 102(e) Date Nov. 14, 1997 PCT Filed May 15, 1996 PCT Pub. No. WO96/36894 PCT Pub. Date Nov. 21, 1996This invention relates to a plastic optical fiber having a three-layer structure comprising a core, a cladding and a protective layer wherein the core material is polymethyl methacrylate and the cladding material is a copolymer composed of 20 to 45% by weight of long-chain fluoroalkyl methacrylate units represented by the following formula (1), 54 to 79% by weight of methyl methacrylate units, and 0.05 to 2% by weight of methacrylic acid units. This invention also relates to a plastic optical fiber cable having a four-layer structure wherein the optical fiber cable is produced by covering the aforesaid optical fiber with a jacket layer.CH2=C(CH3)-COO-(CH2)2(CF2)7CF3(1)

We claim: 
     
       1. A plastic optical fiber having a three-layer structure comprising a core, a cladding and a protective layer wherein the core material is polymethyl methacrylate and the cladding material is a copolymer composed of 20 to 45% by weight of long-chain fluoroalkyl methacrylate units represented by the following formula (1), 54 to 79% by weight of methyl methacrylate units, and 0.05 to 2% by weight of methacrylic acid units.   CH.sub.2 ═C(CH.sub.3)--COO--(CH.sub.2).sub.2 (CF.sub.2).sub.7 CF.sub.3( 1)     
     
     
       2. An optical fiber as claimed in claim 1 wherein the cladding material is a copolymer composed of 23 to 35% by weight of long-chain fluoroalkyl methacrylate units, 63 to 75% by weight of methyl methacrylate units, and 0.5 to 2% by weight of methacrylic acid units. 
     
     
       3. An optical fiber as claimed in claim 1 wherein the material of the protective layer is a copolymer composed of 70 to 90 mole % of vinylidene fluoride units and 30 to 10 mole % of tetrafluoroethylene units. 
     
     
       4. An optical fiber as claimed in claim 1 which has a core diameter of 0.5 to 1.5 mm and a numerical aperture of 0.24 to 0.40 and which exhibits a transmission bandwidth of 80 to 340 MHz when measured at a fiber length of 100 m and under full-mode launch conditions, and a transmission loss of not greater than 200 dB/km. 
     
     
       5. An optical fiber as claimed in claim 4 which has a numerical aperture of 0.27 to 0.34 and exhibits a transmission bandwidth of 90 to 250 MHz. 
     
     
       6. An optical fiber as claimed in claim 1 wherein, when the exit far field pattern of light emitted after 100 m propagation is measured under full-mode launch conditions, the ratio of the value obtained by integrating the far field pattern over an exit angle range of -20° to +20° to the value obtained by integrating the far field pattern over the full angle range is not less than 98%. 
     
     
       7. A plastic optical fiber cable having a four-layer structure comprising a core, a cladding, a protective layer and a jacket layer wherein said optical fiber cable is produced by covering an optical fiber as claimed in claim 1 with a jacket layer. 
     
     
       8. An optical fiber cable as claimed in claim 7 which has a core diameter of 0.5 to 1.5 mm and a numerical aperture of 0.24 to 0.40 and which exhibits a transmission bandwidth of 80 to 340 MHz when measured at a fiber length of 100 m and under full-mode launch conditions, a transmission loss of not greater than 200 dB/km, a transmission loss increment of not greater than 1 dB upon bending under 20 mm R/180° conditions, and a number of flexings to break of not less than 10,000 upon repeated flexing under 15 mm R/±90° conditions. 
     
     
       9. An optical fiber cable as claimed in claim 7 wherein, when the exiting far field pattern of light emitted after 100 m propagation is measured under full-mode launch conditions, the ratio of the value obtained by integrating the far field pattern over an exit angle range of -20° to +20° to the value obtained by integrating the for field pattern over the full angle range is not less than 98%. 
     
     
       10. An optical fiber cable having a four-layer structure comprising a core, a cladding, a protective layer and a jacket layer which has core diameter of 0.5 to 1.5 mm and a numerical aperture of 0.24 to 0.40 and which exhibits a transmission bandwidth of 80 to 340 MHz when measured at a fiber length of 100 m and under full-mode launch conditions, a transmission loss increment of not greater than 1 dB upon bending under 20 mm R/180° conditions, and a number of flexings to break of not less than 10,000 upon repeated flexing under 15 mm R/±90° conditions. 
     
     
       11. An optical fiber cable having a four-layer structure comprising a core, a cladding, a protective layer and a jacket layer wherein, when the exiting far field pattern of light emitted after 100 m propagation is measured under full-mode launch conditions, the ratio of the value obtained by integrating the far field pattern over an exit angle range of -20° to +20° to the value obtained by integrating the far field pattern over the full angle range is not less than 98%.